In general, various types of ships are being manufactured to carry liquid cargos on the sea. For example, in order to carry liquid cargos such as LNG (liquefied natural gas), LPG (liquefied petroleum gas), and crude oil, hulls are manufactured in accordance with the features of respective cargos and specific shapes of liquid cargo storage tanks are used to seal and keep the cargos at a low temperature or a high pressure in the hulls.
One of important load conditions in manufacturing the hulls and the liquid cargo storage tanks is sloshing, which means behavior of liquid which applies a strong shock to the inner walls of a storage space (that is, liquid cargo storage tank) when liquid cargos with a free surface rapidly shakes while continuously receiving kinetic energy from movement of a hull, and sloshing is considered in the early stage of manufacturing hulls and liquid cargo storage tanks.
As described above, the shapes of hulls and liquid cargo storage tanks have been designed to minimize sloshing by liquid cargos and sufficiently resist expected sloshing loads, and in this process, ship owners had to accept conditional sailing conditions that limit the load in order to avoid sloshing loads which are structurally difficult to resist. Nevertheless, various problems keep occurred in unexpected damage to liquid cargo storage tanks due to uncertainty of sloshing loads.
The sloshing was a common issue to be solved for the fuel tanks in the aerospace, aerial, and automobile fields, and unlike ships, it was more important for spaceships or airplanes to supply fuel well rather than to simply reinforce the structures of the fuel tanks due to rapid behavior of fluid which is generated by rapid motions such as 360 degrees rotation, so they have solved the sloshing in the way of controlling the flow of liquid cargos, for example, liquid fuel.
In order to prevent such sloshing, the applicant(s) of the present invention has proposed an apparatus for suppressing sloshing which includes a plurality of buoyant floats that float on the surface of liquid, a foam member having an open cell structure to absorb liquid and surrounding the floats, and connecting members connecting adjacent floats, in Korean Patent Registration No. 1043622.
In the apparatus for suppressing sloshing disclosed in Korean Patent Registration No. 1043622, an example that a buoyant block including the foam member surrounding the floats has a cubic shape is proposed.
Since the apparatus for suppressing sloshing disclosed in Korean Patent Registration No. 1043622 is configured to suppress sloshing due to movement of a liquid cargo by moving with the movement of the liquid cargo, on or slight adjacently over the surface of the liquid cargo, the buoyant block of the apparatus for suppressing sloshing continuously hits against the inside of a liquid cargo storage tank.
As described above, since the buoyant block of the apparatus for suppressing sloshing hits against the inside of a liquid cargo storage tank, the cover that covers the surface of the buoyant block, the foam member, and the inside of the liquid cargo storage tank is damaged.
Meanwhile, according to the apparatus for suppressing sloshing disclosed in Korean Patent Registration No. 1043622, when the inside of a liquid cargo storage tank is cooled or heated, transmission of cooling or heating gas to the bottom of the liquid cargo storage tank is reduced by the apparatus for suppressing sloshing. Accordingly, it takes a long time to cool or heat the inside of the liquid cargo storage tank.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.